Difficulty with transitions...

My (just turned) 2 year old has difficulty with transitions. We have a set daily routine and I always discuss things with him as the day progresses and what will be coming next. I offer warnings before transitions (5 minutes left to play before...) and after those 4 minutes I will set a one minute timer and tell him that we have one more minute before we put on our jackets to go to daycare for example. On the odd time he does transition well I make sure I point it out. He is quite verbal and is speaking in sentences and he understands a lot. He is VERY strong willed and emotional at times which I do my best to calmly help him work through those emotions. Is this normal? I see so many kids his age and I feel like we are the only ones struggling with this. Where am I going wrong? I just feel like I am failing him...